Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$214.59	7.102%	$229.8302	$229.83	$229.85	$229.80
Purchase #2	$133.60	7.103%	$143.0896	$143.09	$143.10	$143.10
Purchase #3	$213.91	7.344%	$229.6196	$229.62	$229.60	$229.60
Purchase #4	$6.80	5.462%	$7.1714	$7.17	$7.15	$7.20
Purchase #5	$222.39	10.730%	$246.2524	$246.25	$246.25	$246.30
Purchase #6	$60.33	11.752%	$67.42	$67.42	$67.40	$67.40
Purchase #7	$219.44	7.336%	$235.5381	$235.54	$235.55	$235.50
7 purchase totals =	$1,071.06		$1,158.9213	$1,158.92	$1,158.90	$1,158.90